Abstract
Sapphire is commonly used as substrate for white light emitting diodes. Smooth surface after a grinding process is required to reduce a processing period for fabrication of flat surface. In this paper, surface roughness was controlled by a number of abrasive grains which pass through sample surfaces. This number is obtained by a quantity of abrasive grains on grinding wheel surface, a wheel rotation speed and a table feeding speed. Newly developed diamond grinding wheels are assembled by hexagonal grinding stones, which have layers with abrasive grains at sides of hexagons and filled up porous material without abrasive grains inside of the hexagons. The quantity of diamond grains on a grinding wheel surface is controlled by a size of hexagonal grinding stone and a layer thickness at edge of grinding stone. When the number of abrasive grains that pass through sample surface increases, surface of sapphire becomes smooth. Surface roughness decreases at a larger quantity of diamond grains on a grinding wheel surface, a higher wheel rotation speed and a higher table feeding speed. Surface roughness ground by a conventional wheel which has abrasive grains on all grinding wheel surface is rougher than that by developed diamond grinding wheels. The results indicate that almost abrasive grains on developed diamond grinding wheels are used for grinding of sapphire, and 1/5 of abrasive grains on a conventional wheel are contributed for grinding of sapphire.
